1. Field of the Invention
The present disclosure relates to a navigation device mounted in a vehicle which travels in any driving mode out of an automatic driving mode for travelling irrespective of a driver's driving operations and a normal driving mode for travelling according to the driver's driving operations, a route guidance control method in the navigation device, and a non-transitory computer-readable storage medium storing therein a program for causing a computer to perform processing in the navigation device.
2. Description of the Related Art
In recent years, there has been an enhanced automatic driving technique for causing a vehicle to travel irrespective of driver's driving operations by controlling the steering wheel, the accelerator and the brake while sensing a situation surrounding the vehicle based on video acquired from a plurality of cameras, for example. In such a situation, there is proposed a navigation device mounted in a vehicle which travels in any driving mode out of an automatic driving mode for travelling irrespective of a driver's driving operations and a normal driving mode for travelling according to the driver's driving operations (see JP 2004-125726 A). With the navigation device, when a plurality of route candidates exist between two locations or between the current location and the destination location, a route including a road along which the vehicle can automatically travel is preferentially selected. With such a navigation device, a road along which the vehicle can automatically travel without the need of the driver's driving operations is easily included in the route along which the vehicle is to be guided, thereby alleviating the load on the driver due to driving operations.
With the navigation device, however, when the vehicle travels in the automatic driving mode along a road capable of automatic driving without the need of route guidance, an audio guidance for route guidance or guidance display such as travelling lane designation, right- or left-turn designation, or straight designation is made, and thus audio output for such a route guidance or guidance display output is troublesome for the driver. In particular, if audio output for route guidance or guidance display output interrupts while music contents or video contents are being output in the vehicle travelling in the automatic driving mode, the music contents or video contents are difficult to listen to or view, and the passengers may feel uncomfortable.